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Gearbox mount renewal

Locosaki

Well-known member
Joined
3 Jul 2016
Messages
409
I had my car in for an MOT and the tester noticed my gearbox mount is split, anyone got any info on what is involved, I had a search through some old posts and some say this is a box out job. It's on a manual C4 if that makes any odds
 
Alex, what are your thoughts on the gearbox inserts now that you've had them fitted for a month or so, has the NVH settled or are you still thinking that they require some modification?

Thanks,
 
They are much 'smoother' than when 1st fitted but there is still a noticeable amount of nvh once wound above 3k rpm. I'm back on another 2.5k trip in 4 weeks and think I'll replicate infrasilver's mod before I go. Gotta admit though, the handling on those Southern French back roads was imense with these fitted - taking hairpins at breakneck speed and didn't even get the psm light flashing.
 
Iain, thanks for the link, not something I'll be doing myself by the looks of it.

So can th poly still be fitted knowing the original mount is split
 
Depending what you mean by split, I would've thought so. I'm still flumaxed as to how he knows it's split as even with the undertray removed, you couldn't tell without removing the carrier brackets. Personally I think the tester is talking out his rectum.
 
Depending how bad the split is the inserts are a fix for it.

Maybe the under tray is missing but one thing that's certain is the mount will be degraded and perishing by now if its the oem fitted one.

On these cars the nose of the gearbox is only supported with one bush and wasn't really adequate imo to the heavier water cooled engine and box, more power and drive to the front etc, the earlier cars ie <3.2 had a total of 4 mounts.

Wayward, vague handling and hard shifting are symptoms its on the way out or 15 years age/80k+ miles.
 
I'm happy with mine with the modification now it has bedded in, it did take a couple of thousand miles but it's pretty much perfect now. The engine and box feel more a part of the car, I don't have any noticeable NVH and I have plenty of other poly bushes on the suspension.
 
:thumb: you've talked me into shaving mine.
 
Infrasilver, I must have missed your bush shaving antics!

I assume that you removed some material from the sides of the insert so that it's a bit more isolated from the chassis and therefore less NVH?
If that is so would the insert not wiggle its way out of gearbox mount holes slightly into the free space that you have created by removing the material?

Any info/pics appreciated.
Many thanks,
 
He's done a write up on it on his to list thread. They wont wiggle out as the centre part of the outer 'ears is clamped between the original bush and the carrier.
 
i went for the function first yellow gearbox mount on the GT3 together with some Torque solutions semi sold engine mounts.

major difference and the car just handles even better than before. NVH is minimal but you can really hear and feel the mezger when winding it up

see in this thread: http://911uk.com/viewtopic.php?t=121777&start=20

the oem gearbox mounts are very soft compared to powerflex and function first...the gear change is just lovely and solid now. well worth doing.

mind you new mounts in OEM spec are going to be better than some 5 year old jobbies and its a fairly quick job once you get all the plates out the way and plastic under cover bits.
 
I've been having a look at new mounts, does the C4 have 2 ? Design 911 have 2 listed, rear extension mount, looks like the front mount but larger
 
2 engine mounts at the rear, 1 gearbox mount at the front of the gearbox:

Engine mount:

s-l300.jpg




Gearbox mount:

pic01.jpg
 

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